Indoor air quality guidelines from across the world: An appraisal considering energy saving, health, productivity, and comfort.

Buildings are constructed and operated to satisfy human needs and improve quality of life. Good indoor air quality (IAQ) and thermal comfort are prerequisites for human health and well-being. For their provision, buildings often rely on heating, ventilation, and air conditioning (HVAC) systems, which may lead to higher energy consumption. This directly impacts energy efficiency goals and the linked climate change considerations. The balance between energy use, optimum IAQ and thermal comfort calls for scientifically solid and well-established limit values for exposures experienced by building occupants in indoor spaces, including homes, schools, and offices. The present paper aims to appraise limit values for selected indoor pollutants reported in the scientific literature, and to present how they are handled in international and national guidelines and standards. The pollutants include carbon dioxide (CO2), formaldehyde (CH2O), particulate matter (PM), nitrogen dioxide (NO2), carbon monoxide (CO), and radon (Rn). Furthermore, acknowledging the particularly strong impact on energy use from HVAC, ventilation, indoor temperature (T), and relative humidity (RH) are also included, as they relate to both thermal comfort and the possibilities to avoid moisture related problems, such as mould growth and proliferation of house dust mites. Examples of national regulations for these parameters are presented, both in relation to human requirements in buildings and considering aspects related to energy saving. The work is based on the Indoor Environmental Quality (IEQ) guidelines database, which spans across countries and institutions, and aids in taking steps in the direction towards a more uniform guidance for values of indoor parameters. The database is coordinated by the Scientific and Technical Committee (STC) 34, as part of ISIAQ, the International Society of Indoor Air Quality and Climate.

Building and indoor environmental quality assessment of Nigerian primary schools: A pilot study.

A total of 15 classrooms went through on-site assessments/inspections, including measurements of temperature (T), and concentrations of carbon monoxide (CO) and carbon dioxide (CO2 ). In addition, the level of surface biocontamination/cleaning effectiveness was assessed by measuring adenosine triphosphate (ATP) levels on students' desks. Based on the data, the quality of facilities in the buildings was low. Classroom occupancy exceeded ASHRAE 50 person/100 m2 standard in all cases indicating overcrowding. However, concentrations of CO2 remained below 1000 ppm in most classrooms. On the other hand, indoor T was above the recommended levels for thermal comfort in all classrooms. Maximum indoor CO was 6 ppm. Median ATP concentrations on the desk tops were moderately high in all schools. The use of open incinerators and power generator sets near classrooms, which was suspected to be the main source of CO, should be discouraged. Improved hygiene could be achieved by providing the students access to functioning bathroom facilities and cafeteria, and by effective cleaning of high contact surfaces such as desks. Although ventilation seems adequate based on CO2 concentrations, thermal comfort was not attained especially in the afternoon during extreme sunlight. Therefore, installing passive and/or mechanical cooling systems should be considered in this regard.

Modeling Associations between Principals' Reported Indoor Environmental Quality and Students' Self-Reported Respiratory Health Outcomes Using GLMM and ZIP Models.

BACKGROUND: The aim of this paper was to examine associations between school building characteristics, indoor environmental quality (IEQ), and health responses using questionnaire data from both school principals and students. METHODS: From 334 randomly sampled schools, 4248 sixth grade students from 297 schools participated in a questionnaire. From these schools, 134 principals returned questionnaires concerning 51 IEQ related questions of their school. Generalized linear mixed models (GLMM) were used to study the associations between IEQ indicators and existence of self-reported upper respiratory symptoms, while hierarchical Zero Inflated Poisson (ZIP)-models were used to model the number of symptoms. RESULTS: Significant associations were established between existence of upper respiratory symptoms and unsatisfactory classroom temperature during the heating season (ORs 1.45 for too hot and cold, and 1.27 for too cold as compared to satisfactory temperature) and dampness or moisture damage during the year 2006-2007 (OR: 1.80 as compared to no moisture damage), respectively. The number of upper respiratory symptoms was significantly associated with inadequate ventilation and dampness or moisture damage. A higher number of missed school days due to respiratory infections were reported in schools with inadequate ventilation (RR: 1.16). CONCLUSIONS: The school level IEQ indicator variables described in this paper could explain a relatively large part of the school level variation observed in the self-reported upper respiratory symptoms and missed school days due to respiratory infections among students.

Indoor environmental quality in school buildings, and the health and wellbeing of students.

Poor indoor environmental quality (IEQ) in classrooms may be a risk for health symptoms and cause absence from school. We conducted a comprehensive study in order to assess the connection between IEQ in Finnish elementary school buildings and the health and academic performance of sixth grade students. The specific aim of the present paper was to study the school- or grade-level prevalence of symptoms in relation to IEQ. The school- or grade-level (i.e. group level) prevalence of self-reported symptoms and perceived IEQ was studied using data collected by a health questionnaire comprising 37 questions. The health questionnaire was sent to all 6th grade students in a stratified random sample of 355 elementary schools in Finland. Indoor environmental conditions were assessed with measurements of ventilation rate and thermal conditions of classrooms in a subsample of 56 schools. Altogether 297 elementary schools participated in the health questionnaire study and a total of 4248 questionnaires were returned (estimated response rate 62.6%). The most common weekly symptoms in the spring semester were fatigue (7.7%), stuffy nose (7.3%), and headache (5.5%). However, both mean prevalence values for different symptoms among all 6th grade students and group-level prevalence values for specific symptoms varied considerably. On the group level, the prevalence values most frequently found above 95% CI (calculated for N=15) were wheezing, cough with wheezing, and fever over 37°C. The most frequently reported IEQ factors causing daily inconvenience in classrooms were noise (11.0%) and stuffy air/poor indoor air quality (IAQ) (7.0%), which were also found most frequently above 95% CI on the group level (calculated for N=15), together with self-reported high indoor temperature and dust or dirtiness. Self-reported daily stuffiness/poor IAQ was significantly correlated with measured mean temperatures and ventilation rates in classrooms. High prevalence of students' self-reported stuffiness/poor IAQ may indicate high indoor temperature or low ventilation rate in classrooms. Also high group level prevalence of other IEQ factors and certain symptoms may be indicative of IEQ problems that should be further studied. The results of this study can be used as a reference for assessing the questionnaire-based prevalence of self-reported symptoms among 6th graders, and their association with IEQ in classrooms. For such assessment, the number of students responding to the questionnaire must be carefully considered, also bearing in mind that prevalence values are symptom specific.